A numeric constant stands for a number. This number can be an
integer, a decimal fraction, or a number in scientific (exponential)
notation.^{1}
Here are some examples of numeric constants that all
have the same value:

105 1.05e+2 1050e-1

A string constant consists of a sequence of characters enclosed in double-quotation marks. For example:

"parrot"

represents the string whose contents are ‘`parrot`’. Strings in
`gawk` can be of any length, and they can contain any of the possible
eight-bit ASCII characters including ASCII nul (character code zero).
Other `awk`
implementations may have difficulty with some character codes.

[1] The internal representation of all numbers, including integers, uses double precision floating-point numbers. On most modern systems, these are in IEEE 754 standard format.